1. Field of the Invention
The present invention relates to a light emitting diode, a method for manufacturing a light emitting diode, an integrated light emitting diode, a method for manufacturing an integrated light emitting diode, a light emitting diode backlight, a light emitting diode illumination device, a light emitting diode display, an electronic apparatus, an electronic device, and a method for manufacturing an electronic device. The present invention can be suitably applied to e.g. light emitting diodes employing a nitride III-V compound semiconductor and various kinds of devices and apparatuses employing this light emitting diode.
2. Description of the Related Art
GaN-based semiconductors allow emission of light in the visible range. In recent years, high-intensity light emitting diodes (LEDs) employing the GaN-based semiconductors are being actively developed.
In order for the high-intensity GaN-based LED to have enhanced light extraction efficiency, pure Ag, which has a high reflectivity with respect to light in the blue and green wavelength bands, is frequently used as the material of a p-electrode that forms an ohmic contact to a p-type semiconductor layer.
However, the Ag electrode involves the following problems.
1. Pure Ag originally shows low resistance (is sensitive) to oxidation and sulfuration and thus is readily affected by capturing of oxygen and sulfur therein from an exposure environment so as to suffer from deterioration of its reflectivity. In particular, an Ag film obtained through vacuum evaporation, which is generally used to form the electrode, involves imperfection in the grain boundary structure and so on in the film and hence shows more significant deterioration.
2. The heat resistance of an Ag film is low, and therefore optical properties and electrical properties of an Ag film are readily varied even through heating at a temperature of as low as about 300 to 400° C.
3. Ag itself is extremely easily ionized, which leads to fears of interdiffusion in the device structure, occurrence of whiskers in an LED package due to migration, and other troubles. The presence of water makes the fears more serious.
4. A GaN-based LED is sealed with resin in general. However, deterioration attributed to traces of water and sulfur contained in resin is often found.
In order to prevent, of these problems, the migration of Ag in particular, there has been proposed a solution in which a protective sheet serving as a migration barrier is formed to cover the surface of an Ag electrode formed on a p-type semiconductor layer (refer to e.g. Japanese Patent Laid-open No. 2003-243705 (hereinafter referred to as Patent Document 1)). Furthermore, as the material of the protective sheet, a metal containing at least one of Ni, Ti, W, Al, Cr, Cu, Au, Sn, Rh, Re, and Ru is disclosed.